A blow out preventer (BOP) and pumping tee connection (flow tee) are common wellhead components that are used on most sucker rod pumped wells in the oil industry. These are two separate components that may be mounted one on top of the other. They are connected by bolts passing through holes in abutting flanges. The purpose of the flow tee is to connect the production flowline(s) to the wellhead production tubing. The production flowline(s) are connected to the flow tee by either a threaded connection or flanged connection.
The purpose of the BOP is to provide a means of shutting in a well (sealing off the production tubing) in which a sucker rod is present in the wellbore. The BOP consists of a housing with two ram blocks therein made of pliable elastomers which are squeezed together by advancing toward one another ram screws that are located on opposite sides of the device. The ram blocks seal off the annular area between the rod and the production tubing providing an effective pressure/fluid seal around the polished rod. This finely finished (polished) rod connects the sucker rod string to a driver on the surface. The fine finish on the rod is required as the rod must pass through a packing gland (stuffing box) which seals the exit point of the rod from the wellhead assembly.
In progressive cavity pumped wells a driver above ground spins the sucker rod string to drive a downhole rotational pump. The drive units are typically mounted on, or slung, or hung from the wellhead assembly. Wellhead height is a major concern as excessive height can lead to wellhead instability problems. Also there are serviceability problems due to the height at which the typically heavy and bulky drivehead components are mounted.